The field of the invention is plumbing fixtures, and the invention relates more particularly to toilet fixtures of the type generally referred to as "blow out" toilets.
The standard residential toilet includes a water storage tank. When the toilet is flushed, the water flows by gravity from the tank and into the toilet bowl. The blow out fixture, in contrast, does not utilize a water tank and, instead, the flush valve (flushometer) feeds water under pressure into the trap below the toilet (as well as feeding rinse water into the toilet bowl). Blow out fixtures are more commonly used in institutional applications and are relatively maintenance free as well as being relatively vandal proof.
There has been a trend toward water conservation, and some municipalities are requiring toilet fixtures which consume less water per flush than conventional toilets. The conventional tank type of toilet typically uses between 31/2 and 5 gallons per flush, and designs have been developed which reduce the volume of water usage to consistently below 1.6 gallons. Very low water usage toilets have been designed for specific purposes such as on commercial passenger aircraft. Such reduction has not been made, however, in the blow out style of toilet with flush valve, and it was not believed possible to provide a reliable toilet design that would approach the low volume usage of 1.6 gallons or less per flush. Such low volume usage must be provided even when there is less than optimum water pressure since institutional water pressures can be found to be as low as 32 pounds per square inch static (25 pounds per square inch flow pressure).